They resemble the glasses worn by Phil Laak of the world poker tour. They're cheap, plastic, durable glasses, usually with huge lenses also made out of plastic.

Here's how the name came about (hypothetically) The Unabomber resembles Phil Laak of the world poker tour, who wears those glasses, which is why its called Unabomber glasses.
2) A Skate team in the UK is called Unibomber, and the glasses were named after them.
3) Peeps just straight up called it Unibomber glasses cause it sounds damn sexy.

Since they're so cheap and easy to find, unabomber glasses are a favorite among Neo Nazis. Heil Bush!